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Simple charging system troubleshooting.

40532 Views 57 Replies 23 Participants Last post by  Spockster
No Charts and few numbers.\

So you think you have a bad Stator or R/R ?

I am here to try to make things simple for everybody.I believe in the KISS theory,Keep It Simple Stupid !

Ok, the first thing that Has to Happen is your Stator needs to have the proper AC out put,Yes AC.Set your Meter to Ohms 1k or less.Find the bullet connectors coming from the Stator to the R/R.They are probably burned looking or nasty or both.Unplug all three,don't worry it makes no difference how you plug them back up or solder them together.More on that later.

Check from each of these leads ,coming from the stator out of the engine, One at a time to the engine case.Your readings should be Infinity(OL) or very high resistance,If it is enough to make you continuity alarm ring we might have a problem ,maybe not. Some meters are much more sensitive than others.If it shows no continuity, between each leg(Yellow wire) from the stator it has passed the first hurdle for sure,your stator is not grounded to frame.

Next set your meter to VAC,200 or less.Remember I mentioned AC output,we are now going to test that.Start the bike ( you should have the battery fully charged before testing your charging system BTW) warm up the engine to normal operating temperature. This next part is easier with a helper,but you can do it by yourself.run the engine up to around 3K RPM's and check between any and all combinations of the three leads from the stator,you should have between 40 to 70 VAC .Is the voltage up to snuff ? It may be a little more but it's doubtful unless you have one that has been rewound as heavy duty or high output.Did it pass the test?In order to pass it must have proper voltage between all combinations of A1,A2 and A3,if one combination is very low or no voltage at all you have a bad stator.If it is good ,time to move on.

If it passed the voltage test ,shut down your engine and perform the resistance test you did before you started the engine.Has any thing changed between each stator leg and the engine case? Is it still showing OL or a really high resistance reading?If so your stator is good.Feel very relieved about now.

If not it and it is showing a low resistance reading to the engine ground this is not good,Your stator is probably going to ground when warm.

Is every thing up to par so far.If so your life just got easier.Plug your stator back up or cut those nasty bullet connectors off and solder those wires together and heat shrink them so you don't have to worry about a loose or weak connection there any more.I will note there are some folks who put fuses in those connections.I personally don't like that Idea but its your bike,If they are fused and something down stream from there grounds it can take out one of those fuses and you are running on two legs of a three phase system and loading them even more,which raises the heat in the stator and I believe it can lead to stator failure,JMO ,do what you want.

Now,we are ready to move on,to checking the R/R out put.Time to go to the DC scale on your meter.You do have the seat off don't you? If not take it off now.Check Battery Voltage directly on the battery posts.If your battery is good and charged it should read close to 13 volts.Contrary to popular belief a a 12 V battery that reads 12 VDC is Dead! Charge it up it should read 12.6 or above when fully charged at rest.If it won't charge up or won't hold charge overnight ,you just found your problem.If it needs charging take it out of the bike or at least unhook it from the bike's electrical system to isolate it and test while disconnected.if you have to charge it.Go in the house and do whatever it is you do while not riding and come back later and test the battery voltage.Is it good? Reconnect it.

Now start your bike and warm it up again if you had to let it sit long enough to cool off.Check battery voltage at idle.It may be the same as before or a little less, most unmodified VN7XX's don't charge much if any at idle.with your leads attached to the battery posts run the engine up to around three K rpm's again.At this rpm the charging system should be putting out around 13.6 VDC or so.Are you getting this much voltage.I hope so and your charging system is doing what is supposed to,If not lets move on.

A common problem is a bad connection on the R/R plug.Now it gets fun,if you haven't relocated your R/R it is underneath the battery box and directly over the Goats Belly,so take your left side cover off and see if you can see it.Unplug it and check the terminals on the R/R and its plug on the wiring harness.Check closely,if they are corroded clean them up and I mean, shiny and clean,both sides of the connections.If you cleaned them up good put a little dielectric grease on them and reconnect it.Back to the battery and your voltages.Check them again just like you did before and and see if they are the same .If they are you have a bad R/R or wiring issues and it is time to check the wiring and connections including all the frame and engine grounds,I'll let you go through all that mess alone,you're gonna be a while.

Did the voltage come up to the magic 13+ when revved up ?You fixed it!!! Now go ride!!!
If not start checking the connections and if you clean all the connections and see no improvements It is R/R time.

It is that simple,you can test the R/R values found in the repair manual or in the online manual on here.Let me stress that the R/R readings can be within range and it may still not charge.This why I tell you to check ALL connections before you buy a R/R,it is worth your time even if this not the problem even if you find a bad connection on the R/R .You will enjoy a lot more trouble free miles of riding.

I hope this helps simplify trouble shooting your charging system.I am a firm believer in "start at the start". It all starts with the stator and if it isn't right,the rest doesn't matter.So by all means Check it and the Connectors coming from it FIRST!!! It may save you a bunch of time and grief.

I know this a long post but I would imagine you can do these tests faster than I typed this.
It really is that simple :smiley_th
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For example: "Find the bullet connectors coming from the Stator to the R/R."

I have no idea where these are, which side of the bike they are on, nor what they look like.
The bullet connectors are more in middle of the transmission, right on top or hanging above it. They are plastic covered plugs similar to the ones under the seat for the tail light wiring. The wires on them will be yellow.

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You sure it was a br/wht wire and not a blue wire? Should've been blue, if it wasn't, change it back.

Need to go through the test steps and give us the voltages and ohms.
#3- I got a reading of OL across all combinations of the three yellow wires. Although, at times, it would flash quickly to a high two-digit number and then immediately return to OL. I tried multiple locations on the frame and got the same results at each location.

#4 I get a fraction of a VAC across all combinations.

#5 With a fully charged battery at 13v, I start 'er up and get no fluctuation of voltage at different RPMs. idle=12.xx; 3k=12.xx; 5k=12.xx

I do know that the PO replaced the R/R within the last year or so.
If I leave the bike on the trickle charger overnight, I come out in the morning to a 13v reading on the battery. It starts/runs fine, I can do my commute, park the bike for 7-8 hours, it reads 11.8v when I come back in the afternoon, and starts up fine for the ride home. Seems to not drain very rapidly, but it definitely doesn't seem to be charging on its own. I have a 90mi ride through back roads coming up next week and I'm a little nervous.

Am I in for a stator replacement?
Sounds like it, but on #4, what ac volt setting was the meter set on? And what was the number of the fraction?
Hmmm, yes, it does look like the stator is toast. Very low ac output.

TPE rewind is the best, most reliable stator you can get.
Thanks I emailed him this morning. His site is under construction.

Weird thing- today I rode about 20mi on the highway and once I got out of traffic and was able to go about 50+mph I saw the voltmeter read about 13.5 at 4000rpm for a while. Is this promising, or unrelated?

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You could check out the wiring, I know the three bullet connectors off the stator are known to create problems.

Might also look at the Two Wire mod, known to cure charging system brownouts, among others.

However, you know the stator has tested dead with those three wires disconnected, so it's not looking good.

Have you gone though the testing for the R/R? Stator and R/R were both toast on mine.
Hmm- maybe I did my test wrong. I did my readings by removing the heat shrink around the soldered connections of the three yellow wires going into the R/R. I didn't remove the solder.

I'm not near the bike now. I'll send pics
Yes, the stator leads need to be disconnected for that test. Think you should be able to unplug at the R/R.

If it checks out, then maybe it is brownouts that the Two Wire mod might help. You wouldn't get the intermittent 13v+ if it wasn't charging at all.
Three ways you can go with stator replacement: Engine pull, engine tilt, or the Tux plate mod.

I did the tilt because I didn't want to lift the engine by myself. There's a lot you don't have to disconnect/remove with this option, and the engine stays mostly inside the frame, so closer to realignment. I left the carbs connected, front exhaust manifold, and bevel gear in place. I did however remove the airbox for earshave at the same time, as well as coasters and removal of the air injection system, so all that helped.

Tux mod can be tricky, plenty of posts here, and a member was selling the plate if you're not inclined to make your own. There can be problems with oil leaks, stator/rotor alignment, and metal shavings from the cut if done on the engine. But many have done it successfully.
What's the big benefit of the Tuxedo pod? That you don't have to remove or tilt the engine to replace the stator?

That's it.

Has to be done just right for stator alignment and to prevent oil leaks.
Im trying to test my charging system.
To test I unplugged the R/R my pulling this connector off of it:
View attachment 56043

Then I attempted to locate the bullet plugs. I think these are the right wires, behind the Vulcan vanity plate, coming up from the underside of the bike and connecting to the the wiring harness, but they aremt bullet plugs at all. what do you call these? Maybe they are bullets but theyre too dirty.
View attachment 56044
View attachment 56042

So i tried testing those three wires by unplugging the R/R, setting the meter to ohms at 2k (200 was my only other option down from that), and touching the other lead to the engine along one of the cylinders:
View attachment 56041
I didn’t really understand the readings. When I saw “1” I turned the meter down, as in when it was reading 1 on 2K, I turned it to 200. Then I was getting readings like 20 or 30 on a couple of them. What should I be seeing?

You should see no connection between a stator lead and ground.

Meters use different ways to display an open circuit, mine just shows OL for open loop.

I would retest on a higher scale, and check between the battery negative and engine block to make sure there's a ground for the test.

If it passes the ground test move on to the other tests.

Those three yellow wires are the right ones. Looks like they've been redone, could be bullet or spade connectors, and a lot of tape.
View attachment 56045
Here’s my meter. Set to ohms 200 here’s what I get (with the RR unplugged):
Each wire to engine block: they all start high and start settling around 1.8 but then slowly tick down to 1.5 or so as I sit there.
Battery negative to the same spot on the engine: starts around 1.2 and slowly ticks down to 0.9
If we trust the meter, unfortunately it's showing the stator is shorted to ground. Seems unusual to have all three legs shorted to ground.
Instead of an ohm reading does the meter have a continuity test? Not sure if that’s the symbol right above the “ON” switch. Usually it’ll read continuity and beep if it detects ground. You don’t want to read continuity between the stator and ground.
That's the diode test, diode symbol.

What does your meter show when you touch both leads together on the same setting?
Can you elaborate on why you're saying that and thereby educate me?
Not sure I trust the meter.

I meant it's not usual for all three leads on the stator to be shorted out. It's usually just one.
When I set the meter to 200 ohms, the same as I've been doing on the bike, it reads the same as the bike, and as the battery: 1.5 or so which ticks down to 1.2 or so.
It looks to me like the meter is showing continuity to ground on all three stator fields, or "legs". Each wire is a leg.

It reads a solid connection on the stator to ground, battery to ground, and meter lead to meter lead.

There should be no connection on this stator ground test. According to this meter, the stator is dead.
Sorry Sir, I’m going to have to respectfully disagree, that’s the continuity symbol. A reading of “1.” Means “infinite resistance” or “open” so that’s what to want to see from the leads to ground. Here is my meter on that setting. I didn’t have it in front of me to look earlier.

View attachment 56046
Yours does have the audio symbol beside the diode symbol.

He got 1.xx on all three tests... Lead to lead, battery negative to engine block, and each stator lead to ground.

If 1.xx is open, then the entire test is invalid because there was no ground for testing. Meaning the engine isn't grounded.

Or I'm confused.
I think we just need to talk him through the meter for sanity. When my stator was dead I did the resistance test between leads of the stator but continuity from the lead to the chassis (ground). Maybe I misread the posts but thought he was testing resistance using the 200ohm setting and touching a lead to ground instead of lead to lead.
For the ground test, he should be touching one lead to ground and one lead to each stator wire. A good stator will show no connection to ground.

For the stator resistance test he should be testing between each stator wire. A good stator will show resistance values in the range listed in the manual. (higher than 1.xx)
If the same resistance shows on the multimeter when I touch the leads as when I test any other circuit, the multimeter must be bad, or I can assume there's the same amount of resistance in all the scenarios?
I hate to crowd this thread with trial and error. It's such a helpful thread. I will get a better multimeter that at least passes a resistance test and I will test again.
Either the meter is bad, or all three of those grounds are solid. Except the stator fields shouldn't be grounded.

I just realized what thread we're in.
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